Meat products in order to facilitate storage, transport and processing the turnover of long-term need, must be put materials in cold storage, the mainly purpose of frozen is for storage, if want to use raw materials must be thawed, food processing technoloLD of a program called thaw back to temperature, also is frozen reverse process.
Back to temperature thawing of traditional food processing enterprise generally by air ,water and vacuum condensing steam through heat transfer media to reach the thawing effect,mainly has following ways:
Adopt the temperature difference between product and air and the adjustment of airflow speed make heat through the static pressure gas of the product's surface boundary layer transmission to the frozen body,so that reach the purpose of frozen baody back to temperature thawing.Have flow air,still air and other methods,its characteristic: the strong adaptability,little equipment investment, can be used in all products no matter small products or big products but long time ,low efficiency.
2. Water thawing
Similar with airflow thawing,medium changed to water. Characteristic is sligLDly better than airflow thaw, but the same low efficiency, time is long, and need a lot of water resources.
Above two ways are usually used in traditional processing technoloLD, generally put the frozen products on the frame or trolley,thawing time more than 12 hours.
The thawing process is the process of frozen reverse, during the frozen process, food surface temperature decreased rapidly, the propagation of the bacteria have been seriously inhibited,when the temperature reach -10°C the bacteria completely controlled, and in the thawing process surface area is the first temperature rising area that, because long time thaw, and at the time of the bacteria breeding and restart, for large materials, in the material center has not yet been fully thawed before the actual surface has been corruption, then increase the weigLDlessness rate of raw materials.
3.Microwave back to temperature thawing
Microwave thawing in the high-frequency radiation and electtromagnetic waves,use the polarity of the molecular vibration of elastic collisions with surrounding molecules ,grinding produce heat,warming form the inside material,using this method ro reture temperature have the advantages of low cost,high efficiency,product without bacteria growing and cover less area ect ,other processes can’t be compared.
Microwave thawing technoloLD used in frozen food can be divided into two kinds of temperature adjustment and melting, temperature adjustment generally make refrigeration thawing frozen goods from lower temperature to rise above the freezing point of water around -4 ~ 2°C.At this time the material is still in a solid and more easily cutting processing and so on, this is also frozen processing principle requires.
Microwave thawing mainly have following feaures:
1.Fast thawing speed,high efficiency
Because microwave can go deep material internal heated directly, do not need the conduction process, a piece of meat from 25 kg of -15°Cto-4°C degrees, just finish in two minutes, it is defrosting time from “hour” to “minute”.
2. Save investment,no environment pollution
Saving the shelf and floor space of natural thawing,can be thawed in the package,reduce the requirements of health envirionment,also avoid the waste water sources in the water thawing.
For example,in a beef processing plant ,have 8 wells ,need 24 hours continuous pumping from the underground,in order for the thaw workshop.This is the big waster of water sources.Thawed greasy sewage,increase the burden for the sewage treatment,also cause the loss of oil kind materials.
3. Ensure material nutritious,no corruption
Seafood microwave drying sterilization equipment